Quoting Commander Shepard:" Just being curious. At what age would you be ok with your child experimenting with pot? If you're pro-ganja, would you smoke with them? If you're not ok with it, what would you do to punish them?"
I wouldn't flip out about it an almost any age...but I am not going to "let them" do anything that is illegal. I will tell them not to & why & all of that, I am not sure what I'd do if I caught them doing it. I do not smoke, haven't for ages, but used to & loved it. Then I started to actually care about things like keeping a clean record, or holding down a good paying job & not loosing it to a random drug test, so I stopped before
it ever caused me any problems....
As to what I would do...not sure at all. I think it would at least in part depend on the totality of the situation.